For a mobile terminal such as a cell phone, various types of input apparatus used by a user for operating the terminal have been developed according to functions and/or uses of the terminal. Many mobile terminals are designed to accept inputs by operation in which the user directly presses with his finger mechanical keys or buttons that have previously been arranged on the surface of the terminal body.
The mechanical keys of input apparatus of such terminals are usually arranged previously according to the main use of the terminal and in general, the originally-defined physical arrangement of the keys cannot be modified later.
Incidentally, in recent years, small-sized mobile terminals have various functions as in the case of some cell phones having functions such as a digital camera and a music player. Further, some mobile terminals have many accessory functions other than that for the main use of each terminal and, as in the case of the PDA (Personal Digital Assistants: Handheld terminal) or the like, some mobile terminals have a plurality of main uses such as a scheduling management and an address book in one terminal. For such multifunctional terminals, fixed key arrangement may cause a user to feel inconvenience depending on the function to be used when he performs input operation.
In order to solve such operational inconvenience, for example, Japanese Patent Application Laid-Open No. 2006-311224 discloses a cell phone having an input apparatus in which a touch panel is arranged on a front face of a liquid crystal display screen. The input apparatus of the cell phone is designed so that when an operation key or a button displayed as an image on the display screen is pressed, a touch panel corresponding to the pressed position receives the input.
With respect to such a cell phone, since it is possible to display any key arrangement on the display screen and receive input, keys can be arranged freely. Therefore, each time a function of the terminal is changed, the key arrangement can be changed freely depending on the function. Thus excellent operability can be obtained. For example, when using a digital camera function installed in such a cell phone, keys such as a shutter and a zoom are arranged on the position which is convenient for the user to use. In addition, when inputting characters, it is possible to arrange keys like a keyboard of a personal computer by changing the arrangement of keys on a display unit. Such terminals allow a user to perform input operation by optimizing the input apparatus of one terminal to a plurality of functions individually.
However, with respect to a terminal that employs a touch panel as an input apparatus, the whole surface of the touch panel is flat so that each key can be arranged freely. Therefore, the shape of each key and the boundary between the keys cannot be determined by sensing the physical concavity and convexity of the surface of each key by touching it with one's finger, as in the case of an input apparatus having prearranged mechanical keys and buttons for operation. Thus it is generally difficult for the user to do touch-typing using such an input apparatus.
In particular, as shown in FIG. 9, for example, in the case where characters are input to compose an e-mail message by using a two-screen cell phone 100 having a touch panel, an operation key display unit 120 for performing input operation by pressing the touch panel and an information display unit 110 for displaying input process and the result are usually separated. Therefore, in order to input correctly, it is required for the user to watch carefully the key to be pressed on the key display unit 120 each time he presses a key displayed on the touch panel in order to ensure a correct pressing operation. Further, the user needs to turn his gaze to the information display unit 110 that displays the input result to confirm whether or not the input result is reflected as desired. Thus the user needs to turn his gaze constantly from the key display unit 120 to the information display unit 110 and vice versa.
On the other hand, as shown in FIG. 10 for example, compared to the terminal in which an input unit and a display unit are separated, a terminal 200 having only one input/display unit 210 provided with a touch panel in the front of one display unit, as in the case of the PDA, places less burden on the user who constantly needs to turn his gaze between the two displays when performing input. However, for example, in the case where the terminal 200 displays both an input portion for a videophone function and information of address book, or displays keys for composing an e-mail message and further the result of input performed by using the keys, generally the display unit 210 (having a touch panel) displays them by splitting its display into upper and lower parts and the like as shown in the figure. When the display is split in this manner, each display of the display unit 210 is needed to be smaller or a part thereof is needed to be omitted. However, in the case where a terminal body is required to be downsized as in the case of a mobile terminal, the display unit is also subjected to the restriction of size. Therefore, in the case where each of the keys is displayed smaller to increase the number of keys to be displayed on the key display unit, operability may deteriorate.
As an apparatus that can solve such inconvenience, for example, with respect to one input/display unit, Japanese Patent Application Laid-Open No. 2003-295996 discloses a display apparatus which displays an input unit and a display unit by arranging them on the same portion of the screen to be overlapped. According to the display apparatus, the limited display space of the screen can be used effectively without reducing the display of the input unit and the display unit.
The display apparatus displays a predetermined image on a display unit having a touch panel and further superimposes a keyboard image on the image so that the image is visible through the keyboard image. In this manner, since these images are overlapped each other so that both images can be viewed, the user can perform input operation by using the keyboard superimposed. Therefore, with this display apparatus, the user can perform input operation while viewing display of a plurality of layers (superimposed display layers) on the same screen without reducing the display of two screens and switching the display.
However, for this display apparatus, the two display screens are controlled separately as a “display window for setting” and a keyboard window of “numerical keypad”. Therefore, the display apparatus does not allow input operation to the display window for setting while the numerical keypad is superimposed on the display window for setting and inputs are accepted by using the numerical keypad. In other words, this display apparatus superimposes two layers one another so that the user can view both layers. However, since the display apparatus controls so that input to only one of the layers is accepted, it cannot deal with a terminal designed to accept an input to both of the layers.
As a method for handling input to a plurality of layers generally known, in the case where a plurality of layers are displayed on a display screen and operation input to one of the layers is accepted, a method in which operation input to a layer is accepted after accepting a choice operation by the user to determine a layer to accept an input as an active layer is known. However, with this method, the user needs to perform the choice operation for choosing a layer to be active each time of changing the input layer. Thus the user is forced to perform cumbersome change operation.
In order to deal with such problem, for example, Japanese Patent Laid-Open No. 2005-284592 discloses a technique for superimposing two screens (display layers) one another on one display apparatus 300 and allowing a user to input to any layer without changing the layer.
The display apparatus 300 described in Japanese Patent Laid-Open No. 2005-284592 can perform a dual-view display in which a plurality of images different from each other are displayed simultaneously in a plurality of display directions corresponding respectively to a plurality of points of view to the same display unit. Thus a plurality of viewers can observe respective images from respective view points, such as, for example, image (b) visible from viewer A and image (c) visible from viewer B. Further, with the display apparatus 300, each viewer can input to the display layer being observed by the viewer. For example, the display apparatus 300 can accept input operations from viewer A to icon A and viewer B to icon B.